CHAPTER F. COMPARATIVE REVIEW.- -HYMENOMYCETES. 287 



club-shaped bodies described above producing two or four, seldom a larger number 

 of spores. No great deviations from the ordinary rule occur except in the Tre- 

 mellineae and a few exceptional genera, as Tulostoma (section XC) and Kneiffia J , 

 in which latter the basidia are said to produce only one spore. The ripe spore is 

 always abjointed as a single cell, except in a few Tremellineae and the doubtful case 

 of Agaricus rutilus 2 , and exhibits every gradation in form from spherical to narrowly 

 fusiform. 



Hymenomycetes and Gastromycetes are distinguished from one another by 

 the structure of their compound sporophores, which we will now proceed to describe. 



HYMENOMYCETES. 



SECTION LXXXV. This division differs from the other in having the hymenium 

 on the free outer surface of the compound sporophore at or more commonly before 

 the time of the abjunction of spores. In the simplest cases, such for example as 

 are presented by Corticium, Dacryomyces, Exobasidium, and some species of 

 Hypochnus, the compound sporophores do not vary essentially in form and 

 differentiation from the layers of teleutospores in the Uredineae, such for instance as 

 the layer shown in Fig. 130, if basidia are substituted for the teleutospores. They 

 are therefore flat or cushion-shaped bodies which bear the hymenial layer on the free 

 surface and are attached by the opposite surface to the mycelium or substratum. From 

 these which are the simplest forms there is a passage into more-highly developed forms 

 and chiefly in two directions. In the one case the substratum is vertical and the 

 margin of the compound sporophore which points upwards raises itself from the 

 substratum and continues to grow nearly at right angles to it ; in this way fan-shaped, 

 mussel-shaped, or horse-shoe-shaped sporophores are formed, bearing the hymenium 

 on the surface which looks towards the ground and sterile on the opposite side. In 

 the other case the compound sporophore rises in a vertical, erect position from 

 the usually, it" not always, horizontal substratum and takes the form of the Cap-fungi 

 and club-shaped Hymenomycetes. The former are obconical bodies or funnel- 

 shaped or umbrella-like and borne on a stalk ; in a few cases the hymenium is on 

 the surface which is turned away from the substratum, and therefore on the upper, 

 inner surface in the funnel-shaped form, while the rest of the surface remains sterile, 

 as in Cyphella, Guepinia, Tul. and Exidia. Generally the opposite is the case, and 

 the hymenium is localised on the side towards the substratum, on the surface of 

 the cone and the lower surface of the stalked umbrella, as in Gyrocephalus of Persoon 

 ( = Guepinia helvelloides, Fr.) and most of the Hymenomycetes in the narrow use of 

 the word. In compound sporophores of the latter kind the portion to which the hy- 

 menial surface belongs has the special name of cap or pileus, and is placed on a more 

 or less distinct stalk, the stipes. The term cap or pileus has been extended for 

 convenience sake from this its original signification to the compound sporophore 

 generally in which the hymenial surface looks towards the ground, and therefore 



1 Fries, Hymenomyc. Europ. p. 628. Berkeley and Broome in Ann. and Mag. of Nat. Hist, 

 ser. 4, VII, p. 429. 



2 Leveille in Ann. d. sc. nat. ser. 2, VIII, 328. 



